In conventional particle beam irradiation systems, it is general that an accelerator such as a synchrotron or the like and a treatment room are placed on the same plane. In recent years, in association with enlargement of the particle beam irradiation systems, deformation of the building thereof occurs due to seasonal variation in outside air temperature or due to crustal movement such as ground depression or the like, resulting in wrong alignment and thus in failure of the radiated beam to meet a prescribed performance. In order to deal therewith, in the use of the particle beam irradiation system, there has arisen a need to change its operation parameters for every season, or to periodically execute re-adjustment of the positions, attitudes and the like, of the electromagnets and the like. As a method of establishing alignment at the time of installation of the particle beam irradiation system, there is disclosed a method in which alignment is established after a displacement amount from a preset position, which is given as a reference point in the building or on the apparatus, is calculated (see, for example, Patent Document 1 and Patent Document 2). Meanwhile, in the case where the particle beam irradiation facility is constructed on a narrow ground adjacent to a hospital or the like, a structure in which the accelerator and the treatment room are arranged in vertical relation therebetween, or something like that, is likely to be employed (see, for example, patent Document 3).